Process of manufacturing glass.



- No. 699,766.A Patented Apr. 29, |992.

A. voELKER.

PROCESS 0F MANUFACTURINGGLASS.

(Application led Sept. 27, 1900.)

(I0 Model.)

THE Nonms Pneus cn., PNoTnLn-io., wAsHwuToN. D. c.

arc itself.

UNTTED STaTns Trice.

aTnNT PROCESS OF MANUFACTURING GLASS.

SPECIFICATION forming part of Letters Patent No. 698,766, dated April29, 1902.

(No specimens.)

lo tria, dated July 13, 1900, and in Switzerland,

dated July 14,1 900,) of which the following is a specification.

The reducing fusion of difcultly-fusible materials (ores, metallicoxids, andthe like) by means of the electric Vcurrent has been effected,with the exception of certain special cases, such as the raw materialsfor glass and calcium carbid, in one of two ways. Either the substanceto be fused has been used as a 2o resistance in the circuit,in whichcase it forms itself the resistance or is in intimate contact withanother resistant material, or the substance to be fused is introducedbetween the poles of an electric arc and is heated by the The secondmethod, which considerably exceeds the first in intensity, has alreadybeen used for melting the raw materials in the manufacture of glass.While heating by means of the arc itself has the ad- 3o vantage that thesubstance is heated very rap- 35 to the manufacture of glass has much torecommend it.

This invention relates to an improvement in the manufacture of glass byelectrical heating, which consists in clearing the molten 4o mass-thatis to say, in removing the air bubbles therefrom-by converting it intoan electrical resistance after it has been melted by the arc. In thismanner the clearing process may be hastened. i

The process is as follows: After the raw materials have been fused inthe electric arc, in a crucible, or the like in the known manner themolten mass is poured or allowed to now into a tank or chamber, and intoit is in- 5o troduced a pair of electrodes, by means of which a strongelectric current is passed through the melted mass, which is a feebleconductor of the second class.

conductor in the first instance or becomes a y By this means, accordingto the strength of the current, a more or less powerful but steady anduniform heating of the mass of glass is effected, so that thelatterbecomes mobile, and the gas and air bubbles in it are able to riseand escape easily. This clearing process is of very short duration, andthe uniformity ofthe heating is of essential importance to the product.

The accompanying drawing shows in vertical section a furnace adapted forthis invention.

The hoppers a a', containing the raw material for making the glass,communicate with the fusionchamber c through upwardly-sloping passagescontaining the conveyers b. In the chamber c,- Which is constructed ofreproof material, such as chamotte, are provided the electrodes CZ e,one between each inlet for the raw material and the outlet for the same.Under the chamber c is arranged the refining-pot f, which is alsoconstructed of reproof material. In this pot f are provided perforatedpartitions-Walls g h, preferably of chamotte stone, forming compartments7e Z, in each of which dips an electrode m n, preferably of carbon.Rising from the bottom of this rening-pot there are one or moreoveriiow-pipes 0, open at the top. A basin p is provided under therefining-pot to collect the molten glass.

The raw materials for making the glass are fed continuously by means ofthe conveyers b into the chambers c from the hoppers c. Because thematerials are discharged into the furnace from below and at the sidesthereof between the carbon electrodes d e and the furnacewvalls, asshown in the drawing, it is possible to avoid contaminating vthe glassin the refining-pot f with dust, and at the same time the walls of thefurnace are protected from the intense heat of the electric arc, sincethis never strikes upon the Walls themselves, but always on the rawmaterial which lines them.

The electric arc between the electrodes d e thoroughly melts thematerials. The molten glass iiows from the fusion-chamber into therefining-pot f into which the electrode plates or bundles met ofsuitable dimensions. A

strong electric current is supplied to these IOO electrodes, and theglass thus clarified flows down the overflow-pipes o into the basin p.

The reason for not introducing the electrodes directlyinto the maintank@` is that the contamination and coloration of the glass byparticles from the electrodes may be avoided.

The strength of the current required depends on the size of the furnaceand ou the composition of the material in question. It may, however, beassumed that five amperes for each square millimeter ot' electrode-sur-Aface is a fair maximum.

W'hat I claim, and desire to secure by Letters Patent of the UnitedStates, is-

lVitnesses:

CHARLES LE SUIsPLn, KARL SCHMITT.

